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Date:   Tue, 10 Oct 2023 22:26:55 +0000
In-Reply-To: <20231010-netdev-replace-strncpy-resend-as-series-v1-0-caf9f0f2f021@google.com>
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Subject: [PATCH v1 net-next 2/7] e1000: replace deprecated strncpy with strscpy
From:   Justin Stitt <justinstitt@google.com>
To:     Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     linux-hardening@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Justin Stitt <justinstitt@google.com>
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Precedence: bulk

`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We can see that netdev->name is expected to be NUL-terminated based on
it's usage with format strings:
|       pr_info("%s NIC Link is Down\n",
|               netdev->name);

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.

This is in line with other uses of strscpy on netdev->name:
$ rg "strscpy\(netdev\->name.*pci.*"

drivers/net/ethernet/intel/e1000e/netdev.c
7455:   strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name));

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
10839:  strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name));

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>

---
Note: build-tested only.
---
 drivers/net/ethernet/intel/e1000/e1000_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
index da6e303ad99b..1d1e93686af2 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_main.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
@@ -1014,7 +1014,7 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	netdev->watchdog_timeo = 5 * HZ;
 	netif_napi_add(netdev, &adapter->napi, e1000_clean);
 
-	strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1);
+	strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name));
 
 	adapter->bd_number = cards_found;
 

-- 
2.42.0.609.gbb76f46606-goog